This invention relates to aqueous titanium dioxide pigment slurries and more particularly to enhancing the stability thereof.
It is desirable to handle titanium dioxide pigment in bulk form, especially when large amounts of the pigment are required. An aqueous slurry of the pigment is an advantageous method for such bulk handling. However, a major drawback to the use of such slurries is that they are unstable with the pigment tending to precipitate from the slurry, appreciably cake, and resist return to the initial dispersion-state of the slurry.
Prior proposals attempt to stabilize such pigment slurries by employing a variety of additives such as surfactants, sequestering agents, chelating agents, and dispersing agents, which include citric acid, acetylacetone, polyhydric alcohols or alkali metal salts with amines, etc. Others coat the pigment with oxides of aluminum, propane diols, monoethanol amines, etc. The stability of the titanium dioxide slurry yet remains a problem even in these modified systems.
It has now been discovered that the stability of a titanium dioxide slurry is substantially increased by dispersing titanium dioxide and hard plastic particles together into water to provide a stabilized aqueous slurry of titanium pigment and plastic particles.